This is an interesting question and I have come across this alot of times in my life- from friends and family. Hinduism does not prohibit any of it's followers from keeping a positive attitude towards other religions. It is believed that different religions are like different spokes of a wheel, all pointing and leading to the same central point of the wheel. Similarly all religions (though having their own ideologies and beliefs) point to the same supreme power i.e. "God". Teachings of Ramakrishna believe in the popular saying "Jato math, Tato path" which means that as many number of people, as many number of paths. Ultimately, each and every human being follows a single path which ultimately leads to a common power called god.
Not just the attitude of a "Hindu", we should talk about the attitude of one human being towards the other human being in today's world. Religions is secondary and Humanity is primary. One should not be concerned about other's religious choices or inclination. Similarly, one should also not be concerned about other's sexual orientation and choice. Each human being is born with their own choices and there is no one in the world who can stop them for thinking or feeling what they want to.
I personally don't consider either sexual orientation or religion as choice. For sexual orientation, it's what you're born with. For religion, it's not always by birth, but it is more of a recognition of who you already are.
